Can anyone help me out here? Im at 127,900 miles. The plugs that were in there were the stock ones, and they were burnt toast. So I bought new plugs, everyone said the NGK Iridium IX were good if your car pings a lot so I went with those. $40 shipped was an amazing prize so I had too. Link is below. Problem is now the car is getting about 14 MPG and I always average about 18-19. Bank 6 was full oil so I had it cleaned and the tech replaced the bottom end of the coil pack as well (The rubber piece). Anyone know what the problem could be?

http://www.ebay.com/itm/170753620967...84.m1497.l2649

 

wow no one?

 

my mechanic said tat the oil could be due to the heads not sealing right/leak in the heads. its prob not your coil pack leaking. could be leaking oil still. but i am taking a shot in the dark i am not too sure.

 

127K for a first plug change? Id guess you have some other issues that are still OEM causing the mpg loss in addition to worn O rings, Valve covers (maybe, prob not) and a valve cover gasket

 

Odd for sure, is that the correct oem replacement heat range/plug?

Air pressure good?

Intake/air filter clean?

Running same octane gas?

What plugs/heat range were you previously using?

 

I don't recall the bottom of the "coil pack" being replacable.

 

yah, sounds like the valve cover O-rings are shot

 

Yeah the valve cover is toast. But I FIXED IT!! Did a ECU reset. I went to my local infiniti dealer and they told me when you run old plugs like that it changes your fuel trims. Reset it and it is fine now. Oh and it's not like I choose to change the plugs at 127K, I just bought the car 3 months ago

 

glad you fixed the issue...i hope the previous owner didnt neglect any other maintenance like they did the plugs.... that could lead to bad things down the road

 

Previous owner did 90K service so all the fluids are good and dealer put on new brakes and tires. But other then that nothing was really done so I'm doing them now. Next thing is to change the driver's side valve cover

 

I'm guessing you didn't disconnect the battery when changing the plugs? Anytime plugs or any electrical items are changed you should disconnect the battery before servicing.

 

Noted for future services